Process for the production of 1-(para aminophenyl)-2-methylaminopropanol-1



iaiented Dec. 27, 1932 UNITED STATES MAX OBERLIN, or DARMSTADT, GERMANY PROCESS FOR THE PRODUCTION on l-(PARA ArumorHENYL)-2-METHYLA rN- rRoPANoL-r No Drawing. Application filed July 19, 1930, Serial No.j ;69,265,and in Germany August 7, 1929.

It is well known that the secondary alcoholgroup of l-phenyl-2-methylamino-propanol- 1 is very reactive, when brought into contact with weak oxidizing agents (see e. g. E. Schmidt, Arch. of Pharm. 252, 1914, page 89 By the present invention it has been shown that in contradistinction to these facts 1- phenyl-2-methylamino-propanol-l is not destroyed by the action of cold nitric acid, but transformed into several nitro-derivatives. By the action of nitric acid of a specific gravity of 1.4 on the mentioned starting product l-(para nitrophenyl)-2-methylamino-propanol-l is formed. Instead of nitric acid of the above mentioned strength a mixture of nitric and sulfuric acid (sp. g. 1.8) may be used, the process being carried out in quite the same way. Care must be taken 2:) not to exceed a temperature of the reaction mixture of about C. This can be done by any of the well known methods of cooling.

The so formed 1- (para nitrophenyl) -2- methylamino-propanol-l is transformed to 2:, the corresponding amino-compound by any of the well known methods of reducing nitrogroups. The reduction may be carried out e. g. by hydrogen in statu nascendi (produced by any well known manner, e. g. by the addi- 30 tion of a metal to an acid) or by molecular hydrogen in connection with the use of catalysts, etc., as will be illustrated in the following examples.

As to the use of the new compound it may be pointed out that as is well known the 1-phenyl-2-methylamino-propanol-l is used against respiration defects; the amino-de-' rivative of the afore-mentioned body has the advantage of being less poisonous. 40 Ewamples (1) 50 parts of normal nitrate of l-phenyl- 2-methylamino-propanol-1 are successively added to a mixture of 50 volume-parts sulfuric (sp. g.=1.84) and volume parts nitrio (s'p.- g.=l.4) acid, care being taken that the temperature does not exceed 30 C. During the addition of the substance the mixture is stirred andafter solution has'taken place which will be a short time after adding the substancethe reaction product is poured on 125 parts ice which operation results in the crystallization of the nitrate of the nitroproduct. After settling of somehours (say 23) the crystallization-product is isolated by suitable means, e. g; filtered with suction, washed with water and dried by means of a vacuum or at a temperature not to exceed 100 C. l0 parts of raw-products are obtained which preferably consist of the nitrate of l-para nitrophenyl-2-methylaminopropanol-l; this is proved by the oxidation, whereby the para-nitro-benzoic acid of a melting point'of 238 C. is obtained. By recr'ystallizing the raw-product the pure normal nitrate of 1- (para nitrophenyl) -2-methylamino-propanol-1 is obtained'whichmelts under decomposition at about 171173 C. The

corresponding base crystallizes from ether in v ly more than the amount of hydrogen which corresponds'to three'mols the hydrogenation is stopped; generally the shaking will take 525 hours time; the shaking is carried out under a temperature of l0-50 C. The catalyst is separated and the solution is evaporated to dryness in a vacuum. The residue is dissolved in water and the free base is obtained therefrom in the ordinary way by the addition of alkali. Thereby -90 parts of dry raw-base are obtained. .By recrystallizpanol-l in 500 volume parts of glacial acetic acid 300 volume parts of a solution of stannous chloride in glacial acetic acid (corresponding to 120parts tin) areadded drop by drop at ordinary temperature, while themixture is agitated. After the precipitation is complete the reaction-mixture is heated for about one hour in a water-bath. It is'therr cooled by means of ice for some hours the' pres cipitated double salt of tin is separated by filtration and decomposed in. aqueous solution by means of hydrogen sulfide; tothis' mixture caustic soda is added, until the mix.- ture shows a strong alkaline reaction; thenit is extracted withether. From the ether so? lution the normal 1- (para aminophenyl) -2 methylamino-propanol-l is obtained by .eVap-. oration of the ether in theform of crystals showing a melting point of 11 4 1169 C.

(3) 5 parts of hydrochlorideof raw .normal l-(para nitrophenyl) Q-methyIaminm propanol-l are dissolved in. 200 volume parts of 5% hvdrochloric acid; ata temperature of 0-5 G. afterwards 100, parts of sodiumamalgam of 5% are added in portions of.5 parts each, adding simultaneously to each portion of the amalgam 5 volume parts of hydro.- chloric acid of 25%. After. 2 hours the solution is supersaturated with caustic soda and extracted with ether; From the ether-solution by evaporation the l-(para, amino,- phenyl)-2-methylaminoepropanol' 1 is. Oh.

tained in the form of hard crystals of a melts ing point of. 11 1116" C.

Claims.

1. Process for the productionof l-(para aminophenyl) 2 methylaminoepropanol 1 consisting in the treatment-of a combination.

of 1-phenyl-2-methylamino-propanol-1 and a mineral acid, with nitric acid of'sp. g. 1.4, at a temperature not exceeding 30 0., separating the resulting product, reducing the same,

and finally separating the free base.

2. The compound l-(para aminophenyl)- Q-methylamino-propanol-1 having a melting point of 114-116 0., soluble in water, more difficultly soluble in alcohol and chloroform, very difficultly soluble in ether, insoluble in petrol-ether.

3. Process for the production of 1- (para,

tric acid of sp. g. 1.4, care being taken that the temperature does not exceed 30 (1., separating the resulting nitrate of 1- (para nitrophenyl) -2-methylamino propanol-1, reducing it by one of the well known methods for reducing nit'ro to amino compounds, and finally separa'ti'ng the free base after the addi-.

tion of alkali.

In testimony whereof I have hereunto signed my name.

MAX OBEBLIN. 

